I've been a SAHM mom for 7 years but I've also had several part-time jobs during that time. My first suggestion is to find evening work so your hubby can take care of the kids to cut down on the child-care costs.
I looked into childcare costs and for just 2 kids it wouldn't be worth a part-time job even at $10/hour... all that hassle for only $20 or so at the end of the month. You >really< need to do the math and figure out if it's worth working... for many years, my sister ended up paying to work -- after gas, work clothes, more fast/convenience foods and childcare for 2 toddlers she was actually "earning" -$50 every month! She stopped working and they ended up with more money.
Anyways... look at preschools for jobs as a secretary or a class room aide. I've worked in childcare at MOPS groups and other times at those churches during women's Bible study groups when they offer childcare. The benefit is that I take my children with me (on days they aren't in school/preschool) and they are in their age-appropriate classroom for free. Can't beat free childcare... and most places around here pay $10/hour for such positions. Most preschools give a tuition discount and other perks to employees.
I have many mom friends who work several evenings a week at Starbucks and Kohl's. These places are mom friendly and even part-time employees have benefits. If you can stagger the hours with your husband you cut down or eliminate the need for childcare.
As for preschool vs daycare.... daycare is set up for all day (usually 12 hours) and you pay for the entire 12 hours even if you just drop your kid off for 6-8 hours. They are also year-round and classrooms are divided by age and as soon as your child has a birthday they are moved to the next classroom.
Preschools are more like a school. They have set hours (like 9am-11:30am or 9:30-1:30pm) so everyone arrives/departs at the same time usually with a specific beginning and ending activity (like circle time). They also follow the local public school schedule for fall break, Christmas break, summer vacation, etc. They use the schools' age cut-off so a child who is 3 before Sept 1 will be in the 3 year old class -- and will stay in the classroom, with those same children, until May when preschool lets out for the summer, even if they turn 4 in November. All the kids 'move up' together and friendships are formed and kept that way. Preschools are also much less expensive... my kids have attended preschool and right now for 2 kids (1 is 4 days a week, the other is 2 days a week) we pay $300/month. If that was daycare, for the same number of days, it would be around $300/week! (at least at the 4-5 daycare places around here I called).